INS and diabetes mellitus: Meta-regression (Table 1) showed that the pooled HbA1c reduction significantly interacted with participants’ baseline age (p = 0.032), proportion of female participants (p = 0.017), the baseline HbA1c level (p = 0.018), and gastrointestinal side effect (p = 0.002) but did not interact with baseline body weight or BMI level, duration of diabetes, follow-up period or insulin use.